A flexible new line of power-line carrier equipment [includes discussion]

A new line of apparatus, featuring flexibility, has now been designed to give more functions in a given spectrum under operating conditions encountered in the field. This new line of apparatus contains frequency shift equipment, relaying equipment, and communications equipment. The frequency shift equipment is designed for operation with impulse rate duration, and frequency-type telemetering; for load and supervisory control; for remote and transfer trip; and for teletype. The relaying equipment is suitable for both distance and phase comparison relaying, with push-to-talk communications and other auxiliary functions. The communications equipment is suitable for manual and automatic switched single-frequency operation, and 2-frequency duplex operation, with both code bell and dial signaling. New designs of line coupling tuners and tone equipment to be used with this line have been previously completed. This redesign program was undertaken to accomplish the following eight objectives: 1. Use of new improved components and circuits; 2. Reduction of size of equipment and complete assemblies; 3. Obtaining more channels to relieve frequency crowding; 4. Improved performance at lower cost; 5. Greater reliability; 6. Satisfactory performance under conditions of supply voltage variation and noise experienced in the field; 7. Reduction of radiation and spurious signals; and 8. To offer a complete line of tested standard assemblies of apparatus to meet electric utility needs.